Pump for cryogenic liquids



J. F. KELLEY 3,131,713

May 5, 1964 BUMP FOR CRYOGENIC LIQUIDS Filed March 22. 1960 2 Sheets-Sheet 1 VENT HEAT EXCHANGER INVENTOR. JOHN F. KELLEY.

ATTORNEY.

VENT

May 5, 1964 Filed March 22,' 1960 J. F. KELLEY PUMP FOR CRYOGENIC LIQUIDS 2 Sheets$heet 2 II LL] (9 2 1 I O X LL! INVENTOR.

JOHN F. KELLEY.

ATTORNEY.

United States Patent Ohio Filed Mar. 22, 1960, Ser. No. 16,672 1 Claim. (Cl. 137340) The present invention relates ,to pumps for cryogenic liquids. The trend toward higher pressures in cryogenic phases of missile 'work establishes a need for a simplified relatively trouble-free pump with the capability of producing extreme pressures. The principal object of the invention is to satisify that requirement.

The invention provides a bellows pump suitable for cryogenic application, the bellows pump having the advantage of eliminating the necessity of packings, piston rings, and precision fits.

Another object of the invention is to provide a multistage bellows pump for cryogenic applications, characterized by extremely high presure capabilities.

For a better understanding of the invention, together with further objects, advantagesand capabilities thereof, reference is made to the following description of the accompanying drawings.

In the drawings:

FIG. 1 is a sectional and schematic view taken along the longitudinal axis of a preferred embodiment of bellows pump apparatus in accordance with the invention;

FIG. 2 is an enlarged sectional view of an alternative form of driven end of the FIG. 1 bellows pump;

FIG. 3 is a schematic view, partly in section, of a two-stage pump apparatus in accordance with the invention;

FIG. 4 is a front view, partly in section, showing a commercial embodiment of the invention schematically illustrated in FIG. 1; and

FIG. 5 is a sectional view of the FIG. 4 apparatus as taken along line 5-5 of FIG. 4 and looking in the direction of the arrows.

In FIG. 1 there is shown a dewar or storage container for cryogenic liquids comprising an outer metallic jacket and an inner metallic liquid storage vessel 11, the latter being spaced from the jacket by an evacuated chamber 12. Within the storage container there is mounted a bellows pump, comprising a metallic bellows 13, a stationary end 14, and a driven end 15. The liquid to be pumped is introduced into the bellows from a supply line 16. Interposed between line 16 and intake valve 17 of the pump is a heat exchanger 18. There is also provided an outlet or exhaust valve 9. The valves 17 and 9 correspond to valves 11 and 13, respectively, of U.S. Patent No. 1,341,669 to Porter, or valves 24 and 23, respectively, of US. Patent No. 1,836,344 to Stokes. These valves are well-known prior art components of a bellows pump. Both valves 17 and 9 are immersed in the stored liquid. This heat exchanger is also immersed in the liquid contained in vessel 11 (i.e. stored liqui so that the liquid to be pumped (i.e. pumped liquid) is sub-cooled as it passes through the heat exchanger 18. The stored liquid (indicated by the dashed lines in FIG. 1) is maintained at a predetermined level, such as 8, and at a pressure lower than the pressure of the liquid in the intake line 16. The level of the stored liquid is maintained by valving from a liquid delivery line 30, which branches out from supply line 16. Inserted in line 30 is a liquid level control valve 31. The cryogenic liquid in the storage container is maintained (as by controlled venting) at a lower temperature than that in the intake line. The flow of heat from Within the bellows 13 to the liquid in the storage vessel 11 prevents the formation of gas within the bellows.

3,131,713 Patented May 5, 1964 The driven end 15 of the bellows pump is actuated by a driving rod 19, which projects through an aperture in the dewar, this aperture being sealed by a bellows 20, or other suitable seal or seals. Heat transfer between the bellows and the liquid in the dewar is optionally increased by making one (or both) of the bellows end fittings in the form of a hollow piston, as illustrated at 15' in FIG. 2, thus increasing the heat transfer surface and reducing the volume of liquid in the bellows.

Thus the invention provides a bellows pump which pumps cryogenic liquids in such a way that the liquid in the bellows is always at a temperature below its boiling point at the pressures within the bellows. The bellows is here used as a reciprocating pump for cryogenic fluids at high pressure, both the bellows and its valves being immersed in a stored cryogenic fluid which is maintained at a lower pressure than that of the liquid supplied to the pump. Since the intake liquid passes through a heat exchanger coil immersed in the same fluid as the bellows, the liquid to be pumped is cooled below its boiling point so that there is removed from the bellows and contents suflicient of the heat generated by pumping to prevent the formation of gas within the bellows.

FIGS. 4 and 5 illustrate a practical embodiment of the invention schematically illustrated in FIGS. 1 and 2. Common reference numerals are used for these figures so that common elements are not further described. In FIG. 4 the driving rod 19 extends through bellowsseal 20 and guide 23 to a suitable reciprocating driving engine 24. The pump is positioned by any suitable means. For example, the fixed end 14 of the pump is positioned by support rods 25, 26 and 27 extending through and secured in apertures formed in a triangular supporting member 28. This member 28 is secured to the fixed end 14. The rods 25, 26 and 27 also extend through siutable apertures in the inner and outer jacket and into the housing of the engine 24.

The invention also provides a multi-stage pump in which the outlet of one stage discharges into the dewar of the next stage. Such an arrangement is illustrated in FIG. 3, wherein the discharge 7 of the first stage is into the storage space 31' of the second stage. The second stage discharge is shown at 7' and the second stage inlet and outlet valves for the bellows pump at 17' and 9'. Each of these stages consists of a bellows pump and valves, immersed in a dewar as described above, and each stage is separately driven. With the use of this arrangement pressure higher than the maximum internal pressure for which a pumping bellows can be designed can be achieved and a large number of stages can be coupled in this sequence, to build up great pressures. The net internal pressure to which the second stage bellows of FIG. 3 is subjected is only that by which the absolute pressure of the liquid is raised in that stage. It will be understood that in the second stage the intake liquid to the bellows is the same liquid as is stored within the dewar, intake line 17 communicating with storage space 31'.

Referring again to FIG. 2, the external diameter of piston 15 may be made sufficiently large to restrain the bellows 13 against substantial buckling or distortion in a direction transverse to its axis. Or this function may be performed in the FIG. 4 embodiment by locating the rods 25, 26 and 27 close to the bellows so that they can restrain the bellows, position the fixed end 14 and guide the driven end 15.

While there has been shown and described what is at present believed to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the proper scope of the invention as defined in the appended claims.

3 I claim: A multistage apparatus for the pumping of cryogenic liquid comprising:

a plurality of double-walled vacuum-insulated containers, each having an interior storage compartment, said containers being designated first, second, and so forth;

a like plurality of bellows-type pumps designated first,

second, and so forth, and defining stages of successively higher pressures, the pumps being individually immersed in the containers;

a liquid intake line for the first pump, said line having a branch for supplying immersion liquid to the storage compartment of the first container;

liquid intake lines for the second and succeeding pumps, each intake line being in communication with the corresponding interior storage compartment;

a heat exchanger immersed in the liquid of the first compartment for sub-cooling liquid applied to the firstpump;

liquid outlet lines for each pump, each of the outlet lines except the last projecting into the interior storage compartment of the next stage;

each of said pumps comprising the following elements:

4 a piston having an actuating rod projecting outwardly through the corresponding container; a stationary end member; a bellows between said piston and said end member; another bellows between said rod and the outer wall of the corresponding container; and means for mounting the stationary end member in fixed position.

References Cited in the file of this patent UNITED STATES PATENTS 1,341,669 Porter June 1, 1920 2,054,710 Okada Sept. 15, 1936 2,580,649 Bludcau Ian. 1, 1952 2,609,668 Dalton Sept. 9, 1952 2,630,757 Cartier Mar. 10, 1953 2,631,538 Johnson Mar. 17, 1953 2,698,576 Strub' Jan. 4, 1955 2,831,325 White Apr. 22, 1958 2,888,879 Gaarder Ian. 2, 1959 2,973,629 Lady Mar. 7, 1961 OTHER REFERENCES Gettzman: High Pressure Pumping Equipment for 25 Cryogenic Liquids, published in Advances in Cryogenic Engineering, volume 4 (1958), pages 231-240. 

